Temperature control method and temperature control system for substrate mounting table

ABSTRACT

There is provided a temperature control method for a substrate mounting table capable of increasing a temperature of a substrate rapidly and reducing a loss of thermal energy. In a susceptor  12  including therein a heater  14,  a coolant path  15  and a coolant reservoir  16  and holding thereon a wafer W on which a plasma etching process is performed, a coolant flows through the inside of the coolant path  15  and the coolant reservoir  16,  and a flow of the coolant is stopped in the coolant reservoir  16  when the heater  14  generates heat.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Japanese Patent Application No. 2009-229828 filed on Oct. 1, 2009 and U.S. Provisional Application Ser. No. 61/257,881 filed on Nov. 4, 2009, the entire disclosures of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present disclosure relates to a temperature control method and a temperature control system for a substrate mounting table that mounts thereon a substrate on which a plasma process is performed.

BACKGROUND OF THE INVENTION

A substrate processing apparatus for performing a plasma process on a wafer as a substrate includes an evacuable chamber that accommodates the wafer therein; a shower head that introduces a processing gas into the chamber; and a susceptor (mounting table) that is positioned to face the shower head within the chamber and serves to mount the wafer thereon and applies a high frequency power to the inside of the chamber. The processing gas introduced into the chamber is excited into plasma by the high frequency power, and positive ions or radicals in the plasma are used for the plasma process of the wafer.

While the plasma process is being performed, the wafer may receive heat from the plasma, and, thus, a temperature of the wafer increases. If the temperature of the wafer increases, radical distribution on the wafer changes and a chemical reaction rate on the wafer also varies. Accordingly, to achieve a desired result in the plasma process, the temperature of the wafer, more specifically, the temperature of the susceptor mounting the wafer needs to be controlled.

In this regard, in accordance with a recent substrate processing apparatus, a heat transfer heater and a coolant path are provided within a susceptor to control the temperature of the susceptor. The heat transfer heater may heat the susceptor, and a coolant flowing through the coolant path may cool the susceptor by transferring heat of the susceptor to the outside. Here, a temperature of the coolant or a flow rate of the coolant may not be accurately controlled, whereas a heat generation amount of the heat transfer heater can be accurately controlled. Thus, in order to accurately control the temperature of the susceptor, the heat transfer heater is operated when necessary while constantly flowing the coolant through the coolant path (see, for example, Patent Document 1).

Patent Document 1: Japanese Patent Laid-open Publication No. H7-183276

In the above-mentioned substrate processing apparatus, however, since the coolant constantly flows through the coolant path, a part of heat from the heat transfer heater may be transferred to the outside of the susceptor by the coolant flowing through the coolant path even when it is attempted to increase the temperature of the susceptor by generating heat from the heat transfer heater. Thus, it takes time to increase the temperature of the susceptor and, also, the temperature of the wafer. Furthermore, since a total amount of heat from the heat transfer heater is not used for the temperature rise of the susceptor, there has been a great loss of thermal energy.

BRIEF SUMMARY OF THE INVENTION

In view of the foregoing, the present disclosure provides a temperature control method and a temperature control system for a substrate mounting table, capable of rapidly increasing a temperature of a substrate while reducing a loss of thermal energy.

In accordance with one aspect of the present disclosure, there is provided a temperature control method for a substrate mounting table mounting thereon a processing target substrate and having therein a heating unit and a coolant path through which a coolant is circulated. The temperature control method includes stopping a flow of the coolant when the heating unit generates heat.

In the temperature control method, a medium having a temperature higher than that of the coolant may be introduced into the coolant path in the process of stopping the flow of the coolant.

In the temperature control method, a mounting surface mounting thereon the substrate may be provided in a top of the substrate mounting table, and the substrate mounting table may further include a coolant reservoir communicating with the coolant path. Further, the mounting surface, the heating unit and the coolant reservoir may be arranged in this sequence from the top of the substrate mounting table. Furthermore, a gas layer may be formed in an upper region of the coolant reservoir by introducing a gas into the coolant reservoir in the process of stopping the flow of the coolant.

In the temperature control method, the gas layer may be formed by a pressurized high-temperature gas.

In the temperature control method, the pressurized high-temperature gas may be coolant vapor.

In the temperature control method, the gas layer may be formed by vapor of the coolant generated by heating and boiling the coolant in the coolant reservoir in the process of stopping the flow of the coolant.

In the temperature control method, a mounting surface mounting thereon the substrate may be provided in a top of the substrate mounting table, and the substrate mounting table may further include a coolant reservoir communicating with the coolant path. Further, the mounting surface, the heating unit and the coolant reservoir may be arranged in this sequence from the top of the substrate mounting table. Furthermore, a heat insulating layer may be formed in an upper region of the coolant reservoir by introducing a multiple number of heat insulating particles into the coolant reservoir in the step of stopping the flow of the coolant.

In the temperature control method, the heat insulating particles may be heated, and then the heat insulating layer may be formed by the heated heat insulating particles of a high temperature.

In accordance with another aspect of the present disclosure, there is provided a temperature control system for a substrate mounting table mounting thereon a processing target substrate and having therein a heating unit, a coolant path and a coolant reservoir communicating with the coolant path. The mounting surface, the heating unit and the coolant reservoir are arranged in this sequence from the top of the substrate mounting table, and a coolant flows through the coolant path and the coolant reservoir. The temperature control system includes a gas layer forming device that forms a gas layer in an upper region of the coolant reservoir by introducing a gas into the coolant reservoir when the heating unit generates heat and a flow of the coolant is stopped.

In the temperature control system, the gas layer forming device may include a heating unit that heats the gas, and the gas layer may be formed by the heated gas of a high temperature.

In accordance with still another aspect of the present disclosure, there is provided a temperature control system for a substrate mounting table mounting thereon a processing target substrate and having therein a heating unit, a coolant path and a coolant reservoir communicating with the coolant path. The mounting surface, the heating unit and the coolant reservoir are arranged in this sequence from the top of the substrate mounting table, and a coolant flows through the coolant path and the coolant reservoir. The temperature control system includes a heat insulating layer forming device that forms a heat insulating layer in an upper region of the coolant reservoir by introducing a multiple number of heat insulating particles into the coolant reservoir when the heating unit generates heat and a flow of the coolant is stopped.

In the temperature control system, the heat insulating layer forming device may include a heating unit that heats the heat insulating particles, and the heat insulating layer may be formed by the heated heat insulating particles of a high temperature.

In accordance with the aforementioned temperature control method for the substrate mounting table, since the flow of the coolant is stopped when the heating unit generates heat, a part of the heat from the heating unit may not be transferred to the outside of the substrate mounting table due to the coolant. Accordingly, the heat from the heating unit can be efficiently used for a temperature rise of the substrate mounting table, so that a temperature of the substrate can be rapidly increased, and a loss of thermal energy can be reduced.

Further, in accordance with the aforementioned temperature control method for the substrate mounting table, since the medium having the temperature higher than the temperature of the coolant is introduced into the coolant path when the heating unit generates heat and the flow of the coolant is stopped, the substrate mounting table can be heated by heat from the high-temperature medium as well as by the heat from the heating unit. Further, a loss amount of heat from the heating unit by the medium can be reduced. Thus, the heat from the heating unit can be more efficiently used for the temperature rise of the substrate mounting table, and the temperature of the substrate can be increased more rapidly.

Furthermore, in accordance with the aforementioned temperature control method and the temperature control system for the substrate mounting table, the gas layer is formed in the upper region of the coolant reservoir when the heating unit generates heat and the flow of the coolant is stopped. Accordingly, the gas layer between the heating unit and the coolant in the coolant reservoir thermally isolates the heating unit from the coolant. Thus, the heat from the heating unit can be more efficiently used for the temperature rise of the substrate mounting table.

Moreover, in accordance with the aforementioned temperature control method and the temperature control system for the substrate mounting table, since the gas layer is formed by the high-temperature gas, the substrate mounting table can be heated by heat of the gas layer as well as by the heat from the heating unit. Furthermore, since a loss amount of heat from the heating unit can be reduced by the gas layer, the heat from the heating unit can be more efficiently used for the temperature rise of the substrate mounting table, and, thus, the temperature of the substrate can be increased more rapidly.

In addition, in accordance with the aforementioned temperature control method for the substrate mounting table, the pressurized high-temperature gas for forming the gas layer may be coolant vapor. The temperature of the coolant vapor is decreased as a result of heat transfer to the substrate mounting table and the coolant vapor is condensed and turned back into the coolant. Then, this coolant is mixed with the coolant already present in the coolant path. Accordingly, the coolant vapor need not be collected after the temperature rise of the substrate, so that a burden of an operator or the like can be reduced. Furthermore, since a coolant concentration or the like may not be changed, deterioration in cooling performance by the coolant can be avoided.

Besides, in accordance with the aforementioned temperature control method for the substrate mounting table, the gas layer is formed by the coolant vapor generated by heating and boiling the coolant in the coolant reservoir, input of additional vapor from the outside is not required. Further, the temperature of the coolant vapor is decreased as a result of heat transfer to the substrate mounting table and the coolant vapor is condensed and turned back into the coolant. Accordingly, the coolant vapor need not be collected after the temperature rise of the substrate, so that a burden of an operator or the like can be reduced. Furthermore, since a coolant concentration or the like may not be changed, deterioration in cooling performance by the coolant can be avoided.

Further, in accordance with the aforementioned temperature control method and the temperature control system for the substrate mounting table, the heat insulating layer including the multiple number of heat insulating particles is formed in the upper region of the coolant reservoir when the heating unit generates heat and the flow of the coolant is stopped. The heat insulating layer between the heating unit and the coolant in the coolant reservoir thermally isolates the heating unit from the coolant. Thus, the heat from the heating unit can be more efficiently used for the temperature rise of the substrate mounting table.

Furthermore, in accordance with the aforementioned temperature control method and the temperature control system for the substrate mounting table, since the heat insulating layer is formed by the heated high-temperature heat insulating particles, the substrate mounting table can be heated by heat of the heat insulating layer as well as by the heat from the heating unit. Furthermore, a loss amount of heat from the heating unit can be reduced by the heat insulating layer. Thus, the heat from the heating unit can be more efficiently used for the temperature rise of the substrate mounting table, and the temperature of the substrate can be increased more rapidly.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting and non-exhaustive embodiments will be described in conjunction with the accompanying drawings. Understanding that these drawings depict only several embodiments in accordance with the disclosure and are, therefore, not to be intended to limit its scope, the disclosure will be described with specificity and detail through use of the accompanying drawings, in which:

FIG. 1 is a cross sectional view illustrating a schematic configuration of a substrate processing apparatus to which a temperature control method for a substrate mounting table in accordance with a first embodiment of the present disclosure is applied;

FIGS. 2A to 2C are process diagrams illustrating the temperature control method for the substrate mounting table in accordance with the first embodiment;

FIG. 3 is a cross sectional view illustrating a schematic configuration of a substrate processing apparatus to which a temperature control method for a substrate mounting table in accordance with a second embodiment of the present disclosure is applied;

FIGS. 4A to 4D are process diagrams illustrating the temperature control method for the substrate mounting table in accordance with the second embodiment;

FIG. 5 is a cross sectional view illustrating a schematic configuration of a substrate processing apparatus to which a temperature control method for a substrate mounting table in accordance with a third embodiment of the present disclosure is applied; and

FIGS. 6A to 6D are process diagrams illustrating the temperature control method for the substrate mounting table in accordance with the third embodiment.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, illustrative embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

A temperature control method for a substrate mounting table in accordance with a first embodiment of the present disclosure will be explained.

FIG. 1 is a cross sectional view illustrating a schematic configuration of a substrate processing apparatus to which the temperature control method for the substrate mounting table in accordance with the first embodiment is applied. The substrate processing apparatus performs a plasma etching process on a wafer for a semiconductor device (below, simply referred to as a ‘wafer’) as a substrate.

A substrate processing apparatus 10 in FIG. 1 includes a chamber 11 that accommodates therein the wafer W for the semiconductor device. A cylindrical susceptor (substrate mounting table) 12 is provided in a lower portion of the chamber 11, and a circular plate-shaped shower head 13 is provided in an upper portion of the chamber 11 to face the susceptor 12.

The susceptor 12 includes an electrostatic chuck (not shown), a heater (heating unit) 14, a coolant path 15 and a coolant reservoir 16 communicating with the coolant path 15. Further, a mounting surface 17 holding the wafer W thereon is provided at a top of the susceptor 12. In the susceptor 12, the mounting surface 17, the heater 14 and the coolant reservoir 16 are arranged in this sequence from the top.

The electrostatic chuck attracts and holds the wafer W electrostatically on the mounting surface 17 by, e.g., a Coulomb force. The heater 14 is composed of a resistor installed in the susceptor 12 so as to correspond to a substantially entire region of the mounting surface 17 of the susceptor 12. The heater 14 may generate heat by a voltage applied from a power supply 18, and the heater 14 may heat the susceptor 12 and, also, the wafer W via the susceptor 12. The coolant reservoir 16 is also provided to correspond to the substantially entire region of the mounting surface 17 of the susceptor 12. The coolant reservoir 16 may cool the susceptor 12 and also cool the wafer W via the susceptor 12 by absorbing heat from the susceptor 12 and from the wafer W by a coolant flowing in the coolant reservoir 16 and releasing the absorbed heat to the outside of the susceptor 12. Further, since a high frequency power supply 19 is connected with the susceptor 12, the susceptor 12 also functions as a lower electrode that applies a high frequency power into a processing space S between the susceptor 12 and the shower head 13. Here, the shower head 13 serves as an upper electrode, and the shower head 13 may be maintained at a ground potential or connected with another high frequency power supply.

The shower head 13 includes a buffer room 20; and a plurality of gas holes 21 that allow the buffer room 20 and the processing space S to communicate with each other. A processing gas is supplied into the buffer room 20 from an external processing gas supply unit (not shown), and the supplied processing gas is introduced into the processing space S through the gas holes 21. In the substrate processing apparatus 10, since the high frequency power is applied into the processing space S, the processing gas introduced in the processing space S is excited into plasma, and a plasma etching process is performed on the wafer W by positive ions or radicals included in the generated plasma.

During the plasma etching process, since the wafer W keeps receiving heat from the plasma, a temperature of the susceptor 12 may be increased. Thus, the substrate processing apparatus 10 is equipped with a coolant circulation system to prevent a temperature rise of the susceptor 12.

The coolant circulation system may include the coolant reservoir 16; the coolant path 15; a coolant pipe 22 provided outside the chamber 11 and connected with the coolant path 15; and a coolant supply unit 23 installed on a part of the coolant pipe 22. The coolant reservoir 16 may be located at a topmost position of the coolant circulation system.

The coolant supply unit 23 may serve as a force-feed pump, and it may force-feed the coolant into the coolant reservoir 16 via the coolant pipe 22 and the coolant path 15 in a direction indicated by an arrow of FIG. 1. Further, the coolant supply unit 23 may also function as a heat exchanger and cool the coolant which has become high temperature after absorbing heat of the susceptor 12. The coolant supply unit 23 is configured to cool the coolant to a relatively low temperature of, e.g., about 10° C. in order to maintain a temperature of the susceptor 12 or to decrease a temperature of the susceptor 12. In this way, the coolant supplied into the coolant reservoir 16 from the coolant supply unit 23 is maintained at a relatively low temperature. By way of example, galden (registered trademark) or fluorinert (registered trademark) is used as the coolant in the present embodiment.

When the plasma etching process is performed in the substrate processing apparatus 10, however, the temperature of the susceptor 12 is increased up to a temperature suitable for the plasma etching process by heat from the heater 14. At this time, a part of the heat from the heater 14 may be transferred to the outside of the susceptor 12 by the coolant flowing through the coolant path 15 or through the coolant reservoir 16, hindering a temperature rise of the susceptor 12. In the present embodiment, in order to solve this problem, a flow of the coolant in the coolant path 15 or in the coolant reservoir 16 is stopped when the temperature rise of the susceptor 12 is attempted by generating heat from the heater 14.

FIGS. 2A to 2C are process diagrams illustrating the temperature control method for the substrate mounting table in accordance with the first embodiment.

Referring to FIGS. 2A to 2C, the coolant supply unit 23 may force-feed the coolant into the coolant reservoir 16 before the heater 14 generates heat, and, thus, the coolant is circulated in the coolant circulation system as indicated by arrows in FIG. 2A.

Then, when the heater 14 generates heat, the coolant supply unit 23 stops the force-feeding of the coolant (FIG. 2B), and, thus, a flow of the coolant in the coolant circulation system is stopped. Accordingly, since the flow of the coolant is stopped in the coolant reservoir 16, the coolant remaining in the coolant reservoir 16 may absorb a part of the heat from the heater 14, while the absorbed heat may not be transferred to the outside of the susceptor 12. Further, since the heater 14 is positioned above the coolant reservoir 16, only the coolant in an upper region of the coolant reservoir 16 may experience a temperature rise due to the part of the heat from the heater 14. Accordingly, convection of the coolant may not occur in the coolant reservoir 16, so that an amount of the heat absorbed from the heater 14 into the coolant in the coolant reservoir 16 may be small. As a consequence, the heat from the heater 14 can be efficiently used for the temperature rise of the susceptor 12.

Subsequently, if the temperature of the susceptor 12 increases up to a temperature suitable for the plasma etching process, the coolant supply unit 23 resumes the force-feeding of the coolant, and, thus, the coolant is circulated in the coolant circulation system as indicated by arrows in FIG. 2C. Accordingly, the susceptor 12 can be maintained at the temperature suitable for the plasma etching process.

In the temperature control method for the substrate mounting table in accordance with the first embodiment, since the flow of the coolant is stopped when the heater 14 generates heat, a part of the heat from the heater 14 may not be transferred to the outside of the susceptor 12 by the coolant. Accordingly, the heat from the heater 14 can be efficiently used for the temperature rise of the susceptor 12, so that a temperature of the wafer W can be increased rapidly, and a loss of thermal energy can be reduced.

Furthermore, since the flow of the coolant is stopped just by stopping the force-feeding of the coolant by the coolant supply unit 23, installation of an additional component in the coolant circulation system of the substrate processing apparatus 10 is not required to perform the temperature control method of the present embodiment. Thus, a cost increase can be avoided.

Moreover, in the temperature control method illustrated in FIGS. 2A to 2C, when the heater 14 generates heat and the flow of the coolant is stopped in the coolant circulation system, a high-temperature medium having a temperature of, e.g., about 80° C. higher than the temperature of the coolant (10° C.) required to maintain the temperature of the susceptor 12 during the plasma etching process may be introduced into the coolant reservoir 16 directly or via the coolant path 15 or the coolant pipe 22. Accordingly, the susceptor 12 can be heated by heat from the high-temperature medium as well as by the heat from the heater 14. Further, a loss amount of heat from the heater 14 by the medium can be reduced, and, thus, the heat from the heater 14 can be more efficiently used for the temperature rise of the susceptor 12. Therefore, a temperature of the wafer W can be increased more rapidly.

In the above-discussed temperature control method for the substrate mounting table in accordance with the first embodiment, although it has been described that the flow of the coolant is stopped in the coolant circulation system, it may be also possible to allow the coolant to flow more slowly than in an ordinary case. In such a case, an amount of the heat transferred to the outside of the susceptor 12 by the coolant can be reduced, so that the temperature of the wafer W can be increased more rapidly than in the ordinary case.

In the above-described substrate processing apparatus 10, the susceptor 12 is provided with the coolant reservoir 16. However, even in case that the susceptor 12 does not have the coolant reservoir 16 but only has the coolant path 15, the same effect can be achieved by stopping the flow of the coolant in the coolant path 15 when the heater 14 generates heat.

Now, a temperature control method and a temperature control system for a substrate mounting table in accordance with a second embodiment of the present disclosure will be explained.

FIG. 3 is a cross sectional view illustrating a schematic configuration of a substrate processing apparatus to which the temperature control method for the substrate mounting table in accordance with the second embodiment is applied.

Since the configuration and the operation of the second embodiment are basically the same as those of the above-discussed first embodiment, redundant description of the same configuration and operation will be omitted, and only distinctive features will be elaborated.

In FIG. 3, a substrate processing apparatus 24 includes a pressure tank (gas layer forming device) 25 on a part of a coolant pipe 22. The pressure tank 25 stores therein a gas, e.g., a nonreactive gas, of relatively high pressure and high temperature and introduces the stored nonreactive gas into a coolant reservoir 16 through the coolant pipe 22 and a coolant path 15 at a preset timing. Here, the nonreactive gas needs to be set to have a pressure and a temperature allowing the nonreactive gas not to be condensed when it is flown into the coolant pipe 22. By way of example, the pressure may be equal to or higher than about 0.2 MPa, and the temperature may be equal to or higher than about 150° C. Further, the pressure tank 25 includes a non-illustrated heater (heating device) to maintain the stored nonreactive gas at the relatively high temperature.

FIGS. 4A to 4D are process diagrams illustrating the temperature control method for the substrate mounting table in accordance with the second embodiment of the present disclosure.

Referring to FIGS. 4A to 4D, the coolant supply unit 23 force-feeds a coolant into the coolant reservoir 16 before the heater 14 generates heat, and, thus, the coolant is circulated in the coolant circulation system as indicated by arrows in FIG. 4A.

Then, when the heater 14 generates heat, the coolant supply unit 23 stops the force-feeding of the coolant. Accordingly, the flow of the coolant in the coolant circulation system is stopped. At this time, the pressure tank 25 introduces a nonreactive gas 26 having a relatively high-temperature and high-pressure into the coolant reservoir 16 via the coolant pipe 22 and the coolant path 15 (FIG. 4B). Since the flow of the coolant is stopped and the coolant reservoir 16 is located at the topmost position of the coolant circulation system, the nonreactive gas introduced into the coolant reservoir 16 is accumulated in an upper region of the coolant reservoir 16.

Subsequently, the nonreactive gas 26 accumulated in the upper region of the coolant reservoir 16 may form a gas layer 27 therein (FIG. 4C). If the gas layer 27 is formed over the entire upper surface within the coolant reservoir 16 and, thus, if an inner wall surface of the upper region of the coolant reservoir 16 and a liquid surface of the coolant in the coolant reservoir 16 are separated, the pressure tank 25 stops the introduction of the nonreactive gas 26. Here, since the gas layer 27 exists between the heater 14 and the coolant in the coolant reservoir 16, the heater 14 is thermally isolated from the coolant in the coolant reservoir 16. Accordingly, heat from the heater 14 may not be absorbed into the coolant in the coolant reservoir 16. As a result, the heat from the heater 14 can be more efficiently used for a temperature rise of the susceptor 12.

Subsequently, if the temperature of the susceptor 12 reaches a temperature suitable for a plasma etching process, a coolant supply unit 23 resumes the force-feeding of the coolant, and the coolant is circulated in the coolant circulation system as indicated by arrows in FIG. 4D. At this time, the nonreactive gas 26 in the coolant reservoir 16 is moved to the outside of the coolant reservoir 16 by the circulated coolant, and, thus, the gas layer 27 may disappear. Thus, a temperature control of the susceptor 12 by the circulated coolant is resumed, and, thus, the susceptor 12 can be maintained at the temperature suitable for the plasma etching process.

In the temperature control method for the substrate mounting table in accordance with the second embodiment, when the heater 14 generates heat and the flow of the coolant in the coolant circulation system is stopped, the gas layer 27 is formed in the upper region within the coolant reservoir 16. Accordingly, the gas layer 27 between the heater 14 and the coolant in the coolant reservoir 16 may thermally isolate the heater 14 from the coolant in the coolant reservoir 16. Thus, the heat from the heater 14 can be more efficiently used for the temperature rise of the susceptor 12.

In the above-described temperature control method for the substrate mounting table of the second embodiment, since the gas layer 27 is formed by the relatively high-temperature and high-pressure nonreactive gas 26, the susceptor 12 can be heated by heat of the gas layer 27 as well as by the heat from the heater 14. Moreover, since a loss amount of heat from the heater 14 can be reduced by the gas layer 27, the heat from the heater 14 can be more efficiently used for the temperature rise of the susceptor 12, and, thus, a temperature of the wafer W can be increased more rapidly.

In order to maintain the gas layer 27 at the relatively high temperature when the gas layer 27 is formed, it may be desirable to pressurize the coolant reservoir 16 after isolating the coolant reservoir 16 and the coolant path 15 from the outside by closing a valve 28 (see FIG. 3) installed in the coolant pipe 22. At this time, since the gas layer 27 is thermally isolated and compressed and thus its temperature increases, the gas layer 27 can be easily maintained at the relatively high temperature.

In the above-discussed temperature control method for the substrate mounting table, although it has been illustrated that the pressure tank 25 stores the nonreactive gas therein and the gas layer 27 is formed by introducing the nonreactive gas into the coolant reservoir 16, the pressure tank 25 may store therein coolant vapor of a relatively high pressure equal to or higher than, e.g., about 0.2 MPa and a relatively high temperature equal to or higher than, e.g., about 120° C., and the gas layer 27 may be formed by introducing the coolant vapor into the coolant reservoir 16. In such a case, the gas layer 27 may be formed by the relatively high-pressure and high-temperature coolant vapor. The temperature of the coolant vapor is decreased as a result of heat transfer to the susceptor 12 and the coolant vapor is condensed and turned into a coolant. Then, this coolant is mixed with the coolant already present in the coolant reservoir 16 or the coolant path 15. Accordingly, the coolant vapor need not be collected after the temperature rise of the wafer W, so that a burden of an operator or the like can be reduced. Furthermore, since a coolant concentration or the like may not be changed, deterioration in cooling performance by the coolant can be avoided.

Moreover, in order to form the gas layer 27, it may be also possible to generate vapor of the coolant by heating and boiling the coolant in the coolant reservoir 16 by the heater 14 or by another heater (not shown) without introducing the nonreactive gas 26 or the additional coolant vapor into the coolant reservoir 16. That is, the gas layer 27 may be formed by the coolant vapor generated from the coolant reservoir 16. In such a case, since an additional device (pressure tank 25) for introducing the nonreactive gas 26 or the like into the coolant reservoir 16 need not be installed in the coolant circulation system, the configuration of the apparatus can be simplified. Furthermore, the temperature of the coolant vapor is decreased as a result of heat transfer to the susceptor 12, and the coolant vapor is condensed and turned back into the coolant, the same effect obtained by introducing the coolant vapor into the coolant reservoir 16 can be achieved.

Now, a temperature control method and a temperature control system for a substrate mounting table in accordance with a third embodiment of the present disclosure will be explained.

FIG. 5 is a cross sectional view illustrating a schematic configuration of a substrate processing apparatus to which the temperature control method for the substrate mounting table in accordance with the third embodiment is applied.

Since the configuration and the operation of the third embodiment are basically the same as those of the first embodiment, redundant description of the same configuration and operation will be omitted, and only distinctive features will be elaborated.

In FIG. 5, a substrate processing apparatus 29 includes a heat insulating particle tank (heat insulating layer forming device) 30 on a part of a coolant pipe 22 upstream of a coolant reservoir 16 in a coolant circulation system. The heat insulating particle tank 30 stores therein a multiple number of spherical heat insulating particles 31 made of a heat insulating material such as heat resistant resin having a smaller density than that of a coolant. The heat insulating particle tank 30 introduces the stored heat insulating particles 31 into the coolant reservoir 16 through the coolant pipe 22 and a coolant path 15. Here, the heat insulating particles 31 are set to have a relatively high temperature equal to or higher than, e.g., about 90° C. Further, the heat insulating particle tank 30 has a non-illustrated heater (heating device) to maintain the heat insulating particles 31 stored in the heat insulating particle tank 30 at the relatively high temperature.

Moreover, the substrate processing apparatus 29 also includes a heat insulating particle collecting unit 32 on a part of the coolant pipe 22 downstream of the coolant reservoir 16. The heat insulating particle collecting unit 32 has therein a space 33 of a certain volume and a collecting net 34 provided in this space 33. The collecting net 34 filters the coolant containing the heat insulating particles 31 flown from the coolant reservoir 16 and separates the heat insulating particles 31 from the coolant in the space 33. The separated heat insulating particles 31 are taken out of the heat insulating particle collecting unit 32 along with the collecting net 34 and stored again in the heat insulating particle tank 30.

FIGS. 6A to 6D are process diagrams illustrating the temperature control method for the substrate mounting table in accordance with the third embodiment.

Referring to FIGS. 6A to 6D, a coolant supply unit 23 force-feeds the coolant into the coolant reservoir 16 before a heater 14 generates heat, and, thus, the coolant is circulated in the coolant circulation system as indicated by arrows in FIG. 6A.

Then, when the heater 14 generates heat, the coolant supply unit 23 stops the force-feeding of the coolant. Accordingly, a flow of the coolant in the coolant circulation system is stopped. At this time, the heat insulating particle tank 30 introduces the heat insulating particles 31 of a relatively high-temperature into the coolant reservoir 16 via the coolant pipe 22 and the coolant path 15 (FIG. 6B). Since the flow of the coolant is stopped and the density of the heat insulating particles 31 is smaller than the density of the coolant, the heat insulating particles 31 introduced into the coolant reservoir 16 are accumulated in an upper region of the coolant reservoir 16.

Subsequently, if the heat insulating particles 31 accumulated in the upper region of the coolant reservoir 16 forms an heat insulating particle layer (heat insulating layer) 35 therein (FIG. 6C), the heat insulating particle tank 30 stops the introduction of the heat insulating particles 31. Here, since the heat insulating particle layer 35 exists between the heater 14 and the coolant in the coolant reservoir 16, the heater 14 is thermally isolated from the coolant in the coolant reservoir 16. Accordingly, heat from the heater 14 may not be absorbed into the coolant in the coolant reservoir 16. As a result, the heat from the heater 14 can be more efficiently used for a temperature rise of the susceptor 12.

Subsequently, if the susceptor 12 reaches a temperature suitable for a plasma etching process, the coolant supply unit 23 resumes the force-feeding of the coolant, and the coolant is circulated in the coolant circulation system as indicated by arrows in FIG. 6D. Accordingly, the heat insulating particles 31 in the coolant reservoir 16 are moved to the outside of the coolant reservoir 16 by the circulated coolant, and the heat insulating particle layer 35 may disappear. Then, a temperature control of the susceptor 12 by the circulated coolant is resumed, and, thus, the susceptor 12 can be maintained at the temperature suitable for the plasma etching process. At this time, in the space 33, the collecting net 34 of the heat insulating particle collecting unit 32 collects the heat insulating particles 31 moved from the coolant reservoir 16 by the coolant.

In the temperature control method for the substrate mounting table in accordance with the third embodiment, when the heater 14 generates the heat and the flow of the coolant is stopped in the coolant circulation system, the heat insulating particle layer 35 is formed in the upper region of the coolant reservoir 16. Since the heat insulating particle layer 35 between the heater 14 and the coolant in the coolant reservoir 16 thermally isolates the heater 14 from the coolant in the coolant reservoir 16, the heat from the heater 14 can be more efficiently used for the temperature rise of the susceptor 12.

In the above-discussed temperature control method for the substrate mounting table in accordance with the third embodiment, since the heat insulating particle layer 35 is formed by the relatively high-temperature heat insulating particles 31, the susceptor 12 can be heated by heat of the heat insulating particle layer 35 as well as by the heat from the heater 14. Moreover, since a loss amount of heat from the heater 14 can be reduced by the heat insulating particle layer 35, the heat from the heater 14 can be more efficiently used for the temperature rise of the susceptor 12, and, thus, a temperature rise of the wafer W can be achieved more rapidly.

In the above-described embodiments, the substrate on which the plasma etching process is performed is not limited to the wafer for the semiconductor device, but it may be any of various kinds of substrates for use in a FPD (Flat Panel Display) including a LCD (Liquid Crystal Display), a photomask, a CD substrate, a print substrate, or the like. 

1. A temperature control method for a substrate mounting table mounting thereon a processing target substrate and having therein a heating unit and a coolant path through which a coolant is circulated, the method comprising: stopping a flow of the coolant when the heating unit generates heat.
 2. The temperature control method of claim 1, wherein, in the process of stopping the flow of the coolant, a medium having a temperature higher than that of the coolant is introduced into the coolant path.
 3. The temperature control method of claim 1, wherein a mounting surface mounting thereon the substrate is provided in a top of the substrate mounting table, the substrate mounting table further includes a coolant reservoir communicating with the coolant path, the mounting surface, the heating unit and the coolant reservoir are arranged in this sequence from the top of the substrate mounting table, and a gas layer is formed in an upper region of the coolant reservoir by introducing a gas into the coolant reservoir in the process of stopping the flow of the coolant.
 4. The temperature control method of claim 3, wherein the gas layer is formed by a pressurized high-temperature gas.
 5. The temperature control method of claim 4, wherein the pressurized high-temperature gas is coolant vapor.
 6. The temperature control method of claim 3, wherein the gas layer is formed by vapor of the coolant generated by heating and boiling the coolant in the coolant reservoir in the process of stopping the flow of the coolant.
 7. The temperature control method of claim 1, wherein a mounting surface mounting thereon the substrate is provided in a top of the substrate mounting table, the substrate mounting table further includes a coolant reservoir communicating with the coolant path, the mounting surface, the heating unit and the coolant reservoir are arranged in this sequence from the top of the substrate mounting table, and a heat insulating layer is formed in an upper region of the coolant reservoir by introducing a multiple number of heat insulating particles into the coolant reservoir in the step of stopping the flow of the coolant.
 8. The temperature control method of claim 7, wherein the heat insulating particles are heated, and then the heat insulating layer is formed by the heated heat insulating particles of a high temperature.
 9. A temperature control system for a substrate mounting table mounting thereon a processing target substrate and having therein a heating unit, a coolant path and a coolant reservoir communicating with the coolant path, wherein the mounting surface, the heating unit and the coolant reservoir are arranged in this sequence from the top of the substrate mounting table, a coolant flows through the coolant path and the coolant reservoir, and the temperature control system comprises: a gas layer forming device that forms a gas layer in an upper region of the coolant reservoir by introducing a gas into the coolant reservoir when the heating unit generates heat and a flow of the coolant is stopped.
 10. The temperature control system of claim 9, wherein the gas layer forming device includes a heating unit that heats the gas, and the gas layer is formed by the heated gas of a high temperature.
 11. A temperature control system for a substrate mounting table mounting thereon a processing target substrate and having therein a heating unit, a coolant path and a coolant reservoir communicating with the coolant path, wherein the mounting surface, the heating unit and the coolant reservoir are arranged in this sequence from the top of the substrate mounting table, a coolant flows through the coolant path and the coolant reservoir, and the temperature control system comprises: a heat insulating layer forming device that forms a heat insulating layer in an upper region of the coolant reservoir by introducing a multiple number of heat insulating particles into the coolant reservoir when the heating unit generates heat and a flow of the coolant is stopped.
 12. The temperature control system of claim 11, wherein the heat insulating layer forming device includes a heating unit that heats the heat insulating particles, and the heat insulating layer is formed by the heated heat insulating particles of a high temperature. 